1. Field of the Invention
The present invention relates to a stamp member and a stamp unit that uses the stamp member, and relates particularly to a stamp member having a porous resin formed with ink-permeable portions and ink-non-permeable portions in its surface by stamp making processes and to a stamp unit that uses such a stamp member.
2. Description of Related Art
Japanese Patent-Publication Application Publication (Kokai) No. HEI-4-363285 (Japanese Patent No. 2853754) discloses a conventional stamp unit shown in FIG. 29. As shown in FIG. 29, the stamp unit includes a stamp member 80 and a holder 83, both formed from the same material, such as polypropylene resin. The stamp member 80 is formed from a porous material through which ink can permeate. The stamp member 80 includes a stamp portion 81 and a non-stamp portion 82 formed around the stamp portion 81. The stamp portion 81 is permeable to ink and formed with characters, symbols, figures, and the like in a protruding shape. The non-stamp portion 82 is formed lower than the stamp portion 81 and is sealed by heat so as not to be permeable to ink.
The holder 83 holds ink and has an opening for letting ink to flow therethrough. The non-stamp portion 82 and a peripheral edge 84 of the holder 83 are fused together by a thermal plate that has been heated to a temperature of 120xc2x0 C. to 180xc2x0 C. and hardened thereafter. In this way, the stamp member 80 and the holder 83 are sealed together so that ink is prevented from leaking.
In order to seal the stamp member 80 and the holder 83 together by thermal fusion as described above, the non-stamp portion 82 need to have a certain width, about 2 mm. This non-stamp portion 82 becomes a margin where no characters are formed during stamping. If the margin becomes large, then it is difficult to precisely align the stamp portion 81 with a desired area of a recording sheet for a stamping operation. As a result, the stamped image may be shifted from the desired area.
Further, it is difficult to precisely position the stamp member 80 onto the holder 83. When the stamp member 80 is stuck on the holder 83 without using some sort of positioning means, the stamp member 80 and the holder 83 may be shifted out of alignment as shown in FIG. 30 It is conceivable to enclose the stamp member 80 inside the holder 83, so that the holder 83 itself serves as a guide member shown in FIG. 31. However, in this case, the holder 83 will surround the periphery of the non-stamp portion 82, so that the margin around stamped images becomes further undesirably large.
Japanese Patent-Application Publication (Kokai) No. HEI-11-78191 discloses a stamp producing device that produces a stamp unit by forming a stamp face on a stamp member of the stamp unit. The stamp member is made from a lower layer and an upper layer, and is supported on a holder. The lower layer is made from a soft porous resin, such as urethane, dispersed with a light energy absorbing material, such as carbon black. The upper layer is made from a hard porous resin that serves to store ink and also apply uniform pressure onto the lower side layer. The stamp producing device forms ink-permeable portions and ink-non-permeable portions in the surface of the lower layer by stamp making processes.
The stamp producing device includes a thermal head and a xenon tube. The thermal head prints characters and images in a transparent original film using a transfer ribbon, thereby preparing a positive original. The holder is set in the stamp producing device such that the lower layer of the stamp member is in confrontation with and pressed against the positive original.
Then, the xenon tube is illuminated. Light from the xenon tube passes through the positive original and illuminates portions of the lower layer of the stamp member. The illuminated portions of the lower layer correspond to the transparent portions of the positive original. The light energy absorbing material heats up illuminated portions of the lower layer, so that illuminated portions fuses and then harden. As a result, these portions of the lower layer are sealed, so that ink cannot pass therethrough. On the other hand, portions of the lower layer that have not been illuminated by the light correspond to printed portions of the positive original, that is, characters and the like printed in the transparent original film. The non-illuminated portions of the lower film remain in their initial condition without being sealed, so that ink can pass therethrough. In this way, the lower surface of the stamp member is formed with ink-non-permeable portions and ink-permeable portions. When a stamp unit with such a stamp member is pressed against a paper sheet during stamp printing, ink exudes out of the stamp unit through only the ink-permeable portions and clings to the paper sheet, thereby stamping a desired character and the like.
A stamp member can formed with a stamp face by, not only a of flash light using the above xenon tube, but also by a thermal head with electrically driven thermal elements or by a thermal press with a heated thermal plate. The heated thermal plate has protrusions and indentations on its surface that correspond to a stamp image.
When forming a stamp face on a stamp member using the flash of light in the above-described manner, it is desirable to interpose a transparent film between the stamp member and the positive original in order to prevent the portions of the porous resin in confrontation with the printed portions of the positive original from being melted and fused by heat transmitted through the printed portions of the positive original, and also to prevent the positive original from sticking to the melted porous resin.
With the thermal head stamp and thermal press stamp making also, it is desirable to perform stamp making with a film interposed between the stamp member and the thermal head or the thermal plate in order to prevent the stamp member and the thermal head or the thermal plate from sticking together. Therefore, stamp producing devices for thermal head stamp making or thermal press stamp making are also configured to have such a film holding mechanism.
It is conceivable to support a film directly on the holder, or to provide a separate mechanism for supporting a film between the holder and the stamp making configuration.
However, providing such a conceivable film holding mechanism has the following problems. First, a film must be attached to the mechanism for each stamp. This would make operations complicated. Also, the film would need to be larger than the stamp surface area, so that the mechanism can properly hold the film. Since more film is used than essentially necessary for its function of stick prevention, material cost would be higher than needed. Also, providing such a separate mechanism for supporting a film would complicate the configuration of the stamp producing device.
Further, in these cases, the porous resin would be exposed until stamp making is performed. Therefore, dust and dirt would easily cling to the surface of the porous resin before stamp making. As a result, the stamp member would have degraded stamp image quality. Moreover, if thermal head stamp making were performed, the film, which is not adhered to the porous resin, could slip out of place, so that a clear stamp image would sometimes not be obtained.
It is an objective of the present invention to solve the above-described problems, and to provide a stamp member, and a stamp unit using the stamp member, capable of preventing a porous resin form sticking using less film without requiring complicated operations.
It is also objective of the present invention to provide a stamp member, and a stamp unit with a stamp member, capable of preventing dirt and dust from clinging to the porous resin of the stamp member.
It is another objective of the present invention to provide a stamp member, and a stamp unit that uses the stamp member, that enables a stamp producing device to have a relatively simple configuration.
It is still a further objective of the present invention to provide a stamp member, and a stamp unit using the stamp member, capable of obtaining clear stamp images by thermal head stamp making processes without substantial slippage between the porous resin and a film.
It is still another objective of the present invention to provide a stamp unit wherein a stamp member is easily and precisely positioned with respect to a holder when producing the stamp unit, thereby reducing a margin of a stamped image and enabling a user to easily align the stamp unit with a target stamp area on a recording sheet.
In order to achieve the above and other objectives, there is a stamp member that have its surface formed with ink-permeable portions and ink-non-permeable portions, including a porous resin having a surface, and a film adhered to the surface of the porous resin for protecting the surface, the film being separable from the porous resin without damaging the surface of the porous resin.
There is also provided a stamp unit including a stamp member and a support member that supports the stamp member, the stamp member having a porous resin having a surface, and a film adhered to the surface of the porous resin for protecting the surface, the film being separable from the porous resin without damaging the surface of the porous resin.
There is further provided a stamp unit producing method of producing a stamp unit comprising the steps of (a) attaching a film on a surface of a porous resin, (b) forming a stamp face on the surface of the porous resin to form ink-permeable portions and ink-non-permeable portions, and (C) peeling the film from the surface of the porous resin.